Metering device



Oct. 17, 1939. A. w. KRAUSE 2,176,673

METERING DEVICE Filed Aug. 27, 1936 2 Sheets-Sheet 1 Oct. 17, 1939. A. w. KRAUSE METERINGy DEVICE Filed Aug. 27, 1956 2 Sheets-Sheet 2 UNITED STATES PATENT oFFlcE METERINGv DEVICE.

Albert W. Krause, Evanston, Ill., assignor to Sears, Roebuck and Co., Chicago, Ill., a corporation of New York 4Application August 27, 1936,-Serial No. 98,138

5 Claims.

My invention relates to electrical'metering devices and has particular application to tuning devices for radio receivers, although it is applicable to other electrical instruments.

' In the tuning of radio receivers, difficulty is frequently experienced in adjusting the tuning to the maximum strength of the signal which it is desired to receive. Tuning along a scale can only be approximately accurate, due to slight variations which occur from time to time in the Wave length of a certain station, and persons with an inaccurate or defective sense of tone find difculty in tuning by ear.

An object of my invention, therefore, is to provide means for metering an electrical device, and

especially for tuning a radio receiver, by means of visual indicia which Will vary according to the strength of the impulse being metered, so that the maximum strength of said impulse can be optically determined with the greatest accuracy.

A further object of my invention is to provide a device of the type referred to wherein the visual indicia will be represented by a light beam projected upon a translucent scale, which beam will vary in size according to the sharpness of the electrical impulse being metered.

A further object is to provide a device of the type referred to wherein the indicia will be in the form of an illuminated triangle a vertex of which points toward a tuning scale, which triangle, as the impulse increases in strength, becomes smaller in area, approaching as a limit a point of light.

Another Objectis to provide, in a device of the type referred to, a plurality of scales of different color, for tuning respective .groups of wave lengths, with means for optionally projecting an illuminated tuning indicia'onto such scales.

Still another object of my invention is to provide in a metering device, a semi-transparent mirror bearing a calibrated scale, with means for projecting a beam of light upon the rear of said mirror, so that said device, when not in operation, will have anon-mechanical appearance, rendering the same especially attractive asV an article of furniture.

Various other objects and advantages will become apparent as the description proceeds.

Referring now to the drawings forming a part of this specification and illustrating a preferred embodiment of my invention,

Figure 1 is a side elevation, partly in section, representing a radio receiver embodying my invention, Y

Figure-2 is a fragmentary elevational view of the front panel of the receiver, showing a tuning scale embodying my invention,

Figure 3 is a sectional view taken substantially along the line 3-3 of Figure 1,

Figure 4 is a sectional view taken substantially along the line 4-4 of Figure 1, and

Figure 5 is a front elevational View, with the front panel removed, showing certain features of the tuning mechanism.

The numeral I Il represents the front panel of a cabinet housing a radio receiving set having certain operative elements which need not be herein discussed, except to say that it includes a variable condenser I2 having a shaft I3. Journaled in the panel I 0 is a shaft I5, retained by bearings I4 and I4; said shaft having a sleeve I6 rotatably mounted thereon. Keyed to the front end of the shaft I5 is a manipulating knob I 1 and independently keyed to the sleeve I6 is a manipulating knob I8. 'Ihe sleeve I6 carries a spur gear 20 which meshes with a gear 2| keyed to the condenser shaft I3, whereby said condenser may be controlled by manipulation of the knoby I8.

'I'he condenser shaft I3 carries at its end opposite to the gear 2I a bevel gear 25 which meshes with a similar gear 26 secured to a shaft 21. Said shaft 21 extends through a bracket 28 fixed to the outside of the condenser housing I2, a suitable journal 29 being provided between the gear 26 and the bracket 2B. Another b-racket 3| is fixed to the shaft 21 by means of a set screw 32. The bracket 3| carries a pair of spaced perforated ears 33, 33, which serve as bearings for a pintle 34. Said pintle serves as a hinge for a pair of spaced ears 35, 35 carried by a housing 31.

Within the housing 31 is a shutter 40, said shutter being in the form of a cylindrical member having a pair of V-shaped slits or perforations 42 arranged in diametrically opposed relation. Said cylindrical shutter is rotatably carried by a bracket 43 which, in turn, is secured to the upper portion of the housing 31. 'Ihe shutter is provided with a shaft 44 and xed to said shaft is a permanent magnet 45. Arranged over the housing 31 is a casing 41 housing an electrical armature 48 and an electromagnet 49 actuated thereby, said armature 48 being electrically connected by means of conduits 50 with an operative element of the receiver, as, for example, in the plate circuit of the detector tube or the intermediate amplifier tubes, whereby the armature coil willvbe energized in accordance with the tuning of the set to the signals received.

It'will be readily apparent that the armature and shutter operate` on the principle of a dfArsonasf val galvano'meter, the position of the shutter about its axis, as represented by the shaft, 44, varying according to the strength of the received signal.

A bracket 52 (Figure 3) is secured to the housing 31 and this bracket carries an electrical lamp 53 housed in a reflector casing 54. An aperture 56 is provided in the rear of the housing 31 for the passage of a light beam from the lamp 53 and a double convex lens 51 is provided in a lens tube 59 for focusing the light which is projected from the lamp 53 and through the shutter 40.

Arranged on the upper wall of the condenser housing I2 is a bracket 60 carrying a plurality of filters indicated at Bla, GIU, and BIc, said lters being mounted in a suitable frame 62. Said filters are formed of any suitable translucentl or transparent material, such .as glass or other plastic, and are differently colored, as, for example, green, red, and yellow, respectively, for a purpose hereinafter described.

'Ihere is also provided in the front wall I0 of the cabinet a plurality of windows 65a, 65h, and 65o, behind which is arranged a translucent screen 66. As shown best in Figure 2, the screen 66 is etched or engraved or otherwise provided with( indicia 68a, 58h, and 68C, representing three groups of wave bands, such as ordinary broadcast, intermediate, and short wave bands, respectively. The screen G6 may, of course, be formed of any suitable translucent material, but I have found it very effective to use for this purpose a semi-transparent mirror. Semi-transparent mirrorsvhave been used before for other purposes and, hence, the method of their manufacture is well known. I find it highly advantageous to use such a device in a radio, since the present tendency is to produce radio cabinets in such form that they will look as much like an article of furniture and as little like a mechanical device as possible. The use of a semi-transparent mirror in lieu of the types'of metering scales heretofore employed imparts to a'radio receiver an improved ornamental appearance and, when the device is not in use, gives it the aspect of an attractive article of furniture.

The spindle I has keyed toits rear end a cam 10 which isbest seen in elevation in Figure 4, said cam having a discontinuous eccentric surface 1I, 1Ia, 1lb and notches 12a, 12b, and'12c.

Said cam is adapted to engage the lower -end of a post 15, saidl post being slidably retainedV by bracket `16Y carried by the condenser housing and a bracket 11 secured to the bracket 28. Said post has at the upper portion thereof a bearing member 18 adapted to engage a member 80 extending rearwardly from the housing 31. A helical tension spring 19 normally urgessaid member 85 into engagement ywith bearing member 18.

Also xed to the shaft I5 is a lever 85 to which is pivoted as at 36 a rock arm 88, the other end of said rock arm being pivoted as at 90 to a` lever 9|. Said lever is pivotally mounted at 93' and serves as a three-way switch element, said switch el-ement being 'so connected' electrically that when said cam is adjusted in a plurality of different positions the radio receiver will be adjusted for the reception of different wave bands. Theseelectrical features of the device are not shown, inasmuch as the same are entirely familiar to thoseskilled in the art.

In the operation of the receiver, the knob I8 is used to control the condenser and hence is used. as the station'selector. As the knob I8 is rotated, the shaft 21'isiturned about its axis, by

means of the bevel gears 25 and 26, carrying with it the shutter 40, armature 48, lamp 53, and associated parts. 'Ihe lamp 53, being illuminated as soon as the switch actuating the receiver is turned on, will project a beam of light through the shutter 4I), the light being focused by the lens 51 and passing through one of the filters and falling upon the screen 66 in the form of a V- shaped or triangular image I, as seen in Figure 2. Said beam, of course, will be clearly visible from the front of the translucent or semi-transparent screen 66. Since the shutter will normally be in a position with the diametrical slits 42 in alignment with the light beam, the image I will' be of maximum size until a broadcase wave is picked up. The current will then flow through the armature 48 and the shutter 40, acting in accordance with the Well known principles of a galvanometer, will be rotated. As the broadcast wave is more accurately tuned, the strength of Vthe `current passing through the armature will increase and the deviation of the shutter 4I! from its normal position will accordingly increase, thus reducing the size of the light triangle, as shown in Figure V2. It will be readilyl apparent that accurate tuning by visual means will thus be very simple, since the illuminated triangle will gradually approach a point as a limit, said point representing the maximum accuracy of tuning.

It will also be seen that the station may be quickly selected roughly, since the light beam projected on the screen is in the shape of a pointer directed toward the numerals of the scale. A further advantage accruing to my invention is that devices embodying the same may be operated in the dark with as much accuracy as in the light.

Tuning the receiver for signals of different Wave bandsis facilitated by means of the plurality of bands of indiciaV on the screen 68, as shown in-Figure 2. Selection of one-of said bands is made by means of the knob I1, controlling the electrical elements of the receiver through mechanism as shown-in Figure 5, and simultaneously actuating the indicating mechanism by means of the cam 10 controlled through the Vshaft I5. When the cam 1U is in such position that the post rests inV the-lowermost notch 12a, the housing-31 will be tiltedv in such a manner that the light' is projected through the uppermost filter Blc andfpasses through the window 65e. Rotation of thecam to the intermediate notch 12b elevates the post15 andy arranges the housing 31 in the position shown in Figure 1 so that the light-is thrown through the filter 6 l b andY through the Window 65h of the front panel; Further rotationof the camto a point where the post 15 rests in the uppermost notch 12e tips the housing 314 to a pointwhere light is projected through the filter Bla and through-the window 65a.

By providing lters of different colors for different Wave bands, the operator can tell at a glance what band is being received.

I am aware that tuning a radio receiver by means of a light beam has been suggested in Smith U. S. Patent 1,997,702, granted April 16, 1935. However, so far as I am aware, I am the first to conceive ofthe use of a pointed beam of light-which approaches a dot` or point of. light as aV limit of tuning accuracy.

Various changes coming within the spirit of my invention will probably suggest themselves to those skilled in the art hence I do not wish toV be limited to the specic form shown or usesf'mentioned, except tothe-*extent indicated in the appended claims, which are to be interpreted as broadly as the state of the art will permit.

I claim:

l. In combination with metering means and means for projecting a beam of light on a graduated screen; a shutter adapted to be operatively connected with the metering means and having spaced walls with V-slots between the screen and the second means, said walls being oppositely movable transverse to the beam by said metering means, said slots being variously registerable relative to the second means to enable a V-shaped beam from the second means to be projected on the screen in similarly-shaped differently-sized V-areas having a common axis, whereby the apexes of the areas will indicate the same reading.

2.'. In combination with metering means, a graduated screen and means for projecting a beam of light toward said screen to be intercepted by the graduated portion thereof; a shutter having walls spaced apart longitudinally of said beam, said walls having slots aligned with Said beam., an edge of one slot cooperating with an edge of the other slot to impart a V-shape to said beam, said slots being movable by said mei tering means toward and away from said beam to vary the cross-sectional area of said beam without shifting the apexes of the areas from a line substantially parallel to the adjacent screen graduation, whereby the apeXes will indicate the same reading.

3. In combination with an electrical circuit adapted to be tuned to resonance, a translucent graduated screen and means for projecting a beam of light onto the graduations; a rotary shutter having a pair of diametrically opposed V-shaped apertures adapted to register with said beam and each other and extending in the same direction from their apeXes and oppositely movable in response to the tuning of the circuit to resonance to register with each other in various degrees and thereby impart a V-shape to the light image projected on the screen through said shutter and vary the size of the image in accordance with the degree of resonance of the circuit, said apertures being arranged to be fully in register with each other and said beam when the circuit is in resonance.

4. In combination with an electrical circuit, a translucent graduated screen and means for projecting a beam of light onto the graduations; a rotary shutter having a pair of diametrically opposed V-shaped apertures through which said beam passes, to impart a V-shape to the light image projected on the screen through said shutter, means for tuning the circuit to resonance, and means cooperating with the tuning means and said Shutter for rotating said shutter so as to vary the alinement of said apertures and thus vary the size of the image in accordance with the degree of resonance of the circuit.

5. In combination with a radio set having a graduated station selector scale illuminated by a lamp; means for tuning the set to resonance with a received signal, means responsive to the tuning of the set for restricting the area illuminated to a V-shape, and means responsive to said tuning means and operative upon said restricting means for reducing the area without substantially shifting the apex of the area transversely of the graduations, as resonance is approached.

,ALBERT W. KRAUSE. 

